Download - Biochem CHO (1)
-
7/30/2019 Biochem CHO (1)
1/67
-
7/30/2019 Biochem CHO (1)
2/67
Carbohydrates
- are a group of naturally occurring carbonyl
compounds (aldehydes or ketones) that alsocontain several hydroxyl groups
- include single sugars (monosaccharides) and
their polymers, the oligosaccharides andpolysaccharides.
-
7/30/2019 Biochem CHO (1)
3/67
- the most abundant organic molecule in nature (each year,
photosynthesis converts more than 100 billion metric tons
of CO2 and H2O into cellulose and other plant products)
- essential for life because of its wide range of function and
widely distributed in plants and animals
- Plants: synthesized from CO2 and H2O through
photosynthesis, store as starch or converted to
cellulose
-
7/30/2019 Biochem CHO (1)
4/67
- Animals: synthesized from Lipids and CHONthrough Gluconeogenesis but the bulk is fromplants
Glucose
- primary CHO, most important source of fuel ofmost organisms
- physiologic sugar since all CHO are convertedto glucose for further metabolism
-
7/30/2019 Biochem CHO (1)
5/67
Functions
1. Source of Energy
- 1 gram of CHO = 4 calories2. Storage form of Energy
- plants (starch), animals (glycogen)
3. Structural component of many organisms
- cell membrane, bacterial cell
4. Provides building blocks for many processes of
body metabolism
-
7/30/2019 Biochem CHO (1)
6/67
-
7/30/2019 Biochem CHO (1)
7/67
Structure
- Carbon containing the functional group (aldehyde or ketone
group) should have the lowest possible number
-Penultimate Carbon: D and L isomer is determined
-
7/30/2019 Biochem CHO (1)
8/67
-
7/30/2019 Biochem CHO (1)
9/67
Haworths Projection Formula (Cyclic form)
- ring is formed due to reactions:
a. aldehyde and the alcohol group (Hemiacetalring)
b. ketone group and alcohol (Hemiketal ring)
- rules: Structure in the left side (above the ring)
Structure in the right side (below the ring)
Bulky group (placed above the ring)
-
7/30/2019 Biochem CHO (1)
10/67
-Pyranose
- the hydroxyl (OH) of5thcarbon reacts with
the 1st
carbon and the oxygen comprising theoxygen ring
- Furanose
- the 1stcarbon reacts with 4rth carbon
- Pyranose form is more stable than furanose form
-
7/30/2019 Biochem CHO (1)
11/67
Classification
A. Monosaccharide (CnH2nOn)
- simple sugars, named based on:
1. the no. of Carbon atoms
2. based on the reaction group present
- aldehyde (aldoses)- ketone (ketoses)
- important monosaccharide:
1. Ribose and Deoxyribose (5C)2. Glucose, Fructose, Galactose (6C)
-
7/30/2019 Biochem CHO (1)
12/67
B. Disaccharides
- yield two molecules of monosaccharide whenhydrolyzed
- e.g. sucrose, lactose, etc.
C. Oligosaccharide- contains 2- 12 monosaccharide units
- e.g. Malto-riose
D. Polysaccharide
- contains more than 10 monosaccharide units
- e.g. Starch, Glycogen etc.
-
7/30/2019 Biochem CHO (1)
13/67
Sugars Exhibit Various Forms of Isomerism
- Isomers are compounds that have the samechemical formula but differ in structural
configuration and properties
- Isomers is due to the presence of asymmetriccarbon (attached to 4 different atoms/groups)
- study of Isomerism is focused on Glucose due to
its clinical importance
-
7/30/2019 Biochem CHO (1)
14/67
-
7/30/2019 Biochem CHO (1)
15/67
- application of polarized light, there is rotationeither to the right (Dextrorotatory (+)) or to theleft (Levorotatory (-))
- D and L isomer is also
known as Enantiomers,
means mirror images ateach other
-
7/30/2019 Biochem CHO (1)
16/67
-
7/30/2019 Biochem CHO (1)
17/67
(3) Alpha and beta anomers
- Isomerism occurs about position 1, the
carbonyl or anomeric carbon atom, togive a mixture:
1. -glucopyranose (38%)
2. -glucopyranose (62%)
- less than 0.3% is represented by and anomers of glucofuranose
-
7/30/2019 Biochem CHO (1)
18/67
Beta : OH in C1 is above the rinAlpha: OH in C1 is below the ring
Ketosis: C2 is involve.
-
7/30/2019 Biochem CHO (1)
19/67
- hemiacetal ring formation (aldehyde) andhemiketal ring (ketose)
- Interco version of alpha and beta is termed as
Mutarotation, rotation is also either Dextro (+)or Levo (-)
- In mutarotation, there is opening of ring of ringand assume free aldehyde or ketone group
-
7/30/2019 Biochem CHO (1)
20/67
(4) Epimers
- Isomers as a result of variations in configurationof the OH and H on carbon atoms 2, 3, and 4 of
glucose
-biologically, the most
important epimers of
glucose are mannose
(C2) and galactose (C4)
-
7/30/2019 Biochem CHO (1)
21/67
(5) Aldose-ketose isomerism
- Fructose has the same molecular formula asglucose but differs in its structural formula (ketogroup in position 2, the anomeric carbon)
- Glucose has potential
aldehyde group in
position 1 of the
anomeric carbon
-
7/30/2019 Biochem CHO (1)
22/67
6. Boat and Chair conformers
- differs in the shape of the ring
- originates from pyranose form- chair is more stable than the boat conformation
-
7/30/2019 Biochem CHO (1)
23/67
Monosaccharide
Aldoses
and
ketoses family
-
7/30/2019 Biochem CHO (1)
24/67
-
7/30/2019 Biochem CHO (1)
25/67
-
7/30/2019 Biochem CHO (1)
26/67
-
7/30/2019 Biochem CHO (1)
27/67
-
7/30/2019 Biochem CHO (1)
28/67
Some hexose derivatives important in biology
-
7/30/2019 Biochem CHO (1)
29/67
Derived sugars
1. Sugar acids
- produced when monosaccharide undergooxidation
C1 - aldonic type (Gluconic acid)
C6 uronic type (Glucoronic acid)
C1 and C6 aldaric (Glucaric acid)
-
7/30/2019 Biochem CHO (1)
30/67
2. Sugar alcohol
- product of reduction of sugar
- e.g. Sorbitol or D-glucitol (sweetener)Mannitol (plasma expander)
3. Sugar amines
- known as amino sugars (NH2 attached in C2)
- constituent of: Antibiotics, Glycoproteins
Glycosaminoglycans
-
7/30/2019 Biochem CHO (1)
31/67
4. Sugar phosphates
- product of phosphorylation of sugar
- phosphorylation important step in glucosemetabolism
5. Deoxy-sugars
- removal of Oxygen from carbon
- Hydroxyl group is replaced with H-ion
- e.g. Deoxyribose (DNA component)
-
7/30/2019 Biochem CHO (1)
32/67
6. Glycosides- formed when CHO is linked to non-CHO suchas aglycone or another sugar through glycosidiclinkage
- aglycone maybe: methanol, phenol, sterol,glycerol or a base (e.g. Adenine)
- can be found in drugs, dyes, vegetables,
animal tissues
- important in the field of medicine
-
7/30/2019 Biochem CHO (1)
33/67
-
7/30/2019 Biochem CHO (1)
34/67
-
7/30/2019 Biochem CHO (1)
35/67
B. Disaccharides
- formed when the anomeric hydroxyl group of
one monosaccharide is bound glycosidically
with one of the OH groups of another (acetal
complementation)
- type of linkage:
1. head to tail (common)
2. head to head (no free functional group,
non-reducing sugar)
.
-
7/30/2019 Biochem CHO (1)
36/67
(1) Maltose
- occurs as a breakdownproduct of the starches
contained in malt(malt Sugar) and as
an intermediate in
intestinal digestion
- the anomeric OH group of one glucose moleculehas an -glycosidic bond with C-4 in a secondglucose residue
-
7/30/2019 Biochem CHO (1)
37/67
2. Lactose (milk sugar,
- is the most important
carbohydrate in the
milk of mammals
- Cows milk contains 4.5%
lactose, while human
milk contains up to 7.5%
- In lactose, the anomeric OH group of galactoseforms a - glycosidic bond with C-4 of a glucose
-
7/30/2019 Biochem CHO (1)
38/67
(3) Sucrose
- serves in plants as
the form in whichcarbohydrates are
transported, and as a
soluble carbohydrate
reserve
- non-reducing sugar
-
7/30/2019 Biochem CHO (1)
39/67
-
7/30/2019 Biochem CHO (1)
40/67
Polysaccharides
- polymer of several molecules of sugars, areubiquitous in nature
- can be classified into three separate groups,based on their differentfunctions
1. Structural polysaccharides-provide mechanical stability to cells,
organs, and organisms
-
7/30/2019 Biochem CHO (1)
41/67
Structural polysaccharide
- structural component of cells and tissues1. Cellulose
2. Chitin
3. Glycoprotein
4. Glycosaminoglycans
-
7/30/2019 Biochem CHO (1)
42/67
2. Waterbinding polysaccharides- are strongly hydrated and prevent cells and
tissues from drying out
3. Reserve/Storage polysaccharides
- serve as carbohydrate stores that releasemonosaccharides as required
- due to their polymeric nature, they areosmotically less active, hence can be storedin large quantities within the cell
-
7/30/2019 Biochem CHO (1)
43/67
Storage polysaccharides
- source of energy or storage form of CHO1. Starch
2. Glycogen
3. Inulin
4. Dextrin
-
7/30/2019 Biochem CHO (1)
44/67
Structure
Homopolysaccharides- contain only a single
type of monomer
Heteropolysaccharides- contains two or more
different kinds
-
7/30/2019 Biochem CHO (1)
45/67
-
7/30/2019 Biochem CHO (1)
46/67
-
7/30/2019 Biochem CHO (1)
47/67
-
7/30/2019 Biochem CHO (1)
48/67
-
7/30/2019 Biochem CHO (1)
49/67
Starch
- the most important vegetable reservecarbohydrate and polysaccharides from plantcell walls
- consist of glucose as building block (glucanor glucosans)
- abundant in fruits- important in human diet (50 70%)
-
7/30/2019 Biochem CHO (1)
50/67
Structure:
1. Amylose
- linear form consisting of 250 300 glucose
units (alpha 1-4 linkage)
- 15 20%, soluble in water, when in solutionform a helix
2. Amylopectin
- branched form with alpha 1-6 linkage in thebranch (every 12 18 glucose units)
- 80 to 85%, water insoluble
-
7/30/2019 Biochem CHO (1)
51/67
-
7/30/2019 Biochem CHO (1)
52/67
Glycogen
- the reserve carbohydrate of higher animals, isstored in the liver and musculature in particular
- formation and breakdown of glycogen are subjectto complex regulation by hormones and otherfactors
- structure: similar to amylopectin but highly
branched (every 8 10 units)
-
7/30/2019 Biochem CHO (1)
53/67
-
7/30/2019 Biochem CHO (1)
54/67
Inulin- a fructose polymer, is used as a starch substitute in
diabetics dietaryproducts
- it serves as a test substance for measuring renalclearance
Chitin
- a homopolymer from 1-4-linkedN-acetylglucosamine,
- most important structural substance in insect andcrustacean shells, thus , the most common animalpolysaccharide
- also occurs in the cell wall of fungi.
-
7/30/2019 Biochem CHO (1)
55/67
Dextrin
- formed in the course of hydrolytic breakdown ofstarch
- yield maltose upon hydrolysis by amylase
- contains 7 10 glucose units
- used in malt preparation for beverages
- widely used in infant feeding which facilitatesdigestions (prevents large heavy curds of milk inthe stomach)
-
7/30/2019 Biochem CHO (1)
56/67
Cellulose
- structural polysaccharide of plants
- linear polymer ofB-D-glucose joined byB 1-4glycosidic bond
- cellobiose as building block
- could not be digested by humans due to lack of
B-1-4 glycosidase enzyme- food sources: Fruits, vegetables and other fibrous
foods
-
7/30/2019 Biochem CHO (1)
57/67
-
7/30/2019 Biochem CHO (1)
58/67
Physiologic function
- serves as a roughage (cleansing of Intestine)
by increasing the fecal bulk thereby decreasingthe transit time of bowel preventing the effectsof toxins and microorganisms in the colon
- decrease in fecal bulk will increase transit timeof bowel, increase exposure to carcinogens(waste product of metabolism or in-situproduction)
-
7/30/2019 Biochem CHO (1)
59/67
Glycoproteins
- high CHON content than CHO
- found in cell membrane or tissues
- widely distributed and perform several functions
- contains sialic acid responsible for its (-) charge
- substances made up of glcoproteins:
a. Blood group Ag
b. Enzymes d. Collagen
c. Transport proteins e. Antibodies (Ab)
-
7/30/2019 Biochem CHO (1)
60/67
Glycosaminoglycans
- known as Mucopolysaccharide or Proteoglycan
- special heteropolysaccharide made up ofUronicacid andAmino sugars as building block
- present in matrix where in collagen, elastin andbone minerals are embedded
- relative to connective tissue function
-
7/30/2019 Biochem CHO (1)
61/67
- responsible for the lubricating function of mucousmembrane
- almost all exist as proteoglycan (uronic acid isattached to a CHON):
a. Chondroitin
b. Heparin
c. keratan
d. Heparan
-
7/30/2019 Biochem CHO (1)
62/67
Types of Glycosaminoglycans and their repeatingDisaccharides
1. Hyaluronic acid
- largest consist of
400 25,000 linearpolymer of repeating
disaccharide
- main constituent ofground substance of
Connective tissues
-
7/30/2019 Biochem CHO (1)
63/67
2. Chondroitin
- acts as water bed
around cells and fibers
- types:
a. Chondroitin-4-SO4
b. Chondroitin-6-SO4
c. Dermatant sulfate
-
7/30/2019 Biochem CHO (1)
64/67
3. Heparin
- naturally occurring
anticoagulant
- present in Mast cells
Lining of arteries
Liver, lungs and skin
-
7/30/2019 Biochem CHO (1)
65/67
4. Keratan sulfate
- present in corner of the eye and nucleus of
Intervertebral disc
- repeating disaccharide:
N-acetylglucosamine-B-1,3-D-galactose
-
7/30/2019 Biochem CHO (1)
66/67
Summary of Function
1. Component of ground substances or C.T.
e.g. Hyaluronic Acid, Chondroitin
2. Structural component of cell membrane
3. Lubricant in joint spaces
e.g. Hyaluronic Acid
4. Anti-coagulante.g. Heparin
-
7/30/2019 Biochem CHO (1)
67/67
END